A $2 billion Government overhaul, including more state homes and universal child support, is needed to fight child poverty, a report from the children's commissioner says.

Russell Wills' final report into child poverty has thrown the ball back to the Government, recommending 78 changes, including enshrining child welfare in law.

However, the Government has already poured cold water on the report, rejecting one big-ticket recommendation and emphasising tight finances.

The report paints a bleak picture of the 270,000 children living in poverty, many of whom regularly go hungry, get sick and live in overcrowded homes.

It says the first step is to create a strategy to monitor child poverty and set ambitious targets for improvement.

Some recommendations are simple and cheap - with a few reflecting existing Government policy - but others could cost billions.

They include scrapping many benefits for parents and replacing them with a universal payment for every child under 5.

It also recommends building 2000 new state homes a year and requiring all rentals to pass a health and safety "warrant of fitness".

The combined changes are estimated to cost the Government between $1.5b and $2b a year and reduce child poverty by up to 40 per cent. The report estimates the economic cost of child poverty to be between $6b and $8b a year.

"It is those on the lowest incomes who are in the greatest need, so any new spending needs to be tightly targeted," she said.

Warrants of fitness for homes, and community hubs, were ideas with "merit" and other suggestions were already being pursued by Government, she said.

Finance Minister Bill English said throwing more money at child poverty would not necessarily solve it. "Too often, governments have, for political reasons, persisted with programmes that have been ineffective and expensive."

But Professor Jonathan Boston, who co-chaired the group that wrote the report, said that, while the cheap options would help, costly and ambitious reform was required for deep and lasting change.

"Making a substantial dent in child poverty can't be done on the smell of an oily rag."

Some of the more costly projects could be shelved until the Government books were in better shape, he said. Others could be funded by diverting money from people who did not have dependent children.

"As resources become available, it is our most needy children that should have the first claim."

Dr Wills said the Government was already acting on child poverty but needed to do more.

"The report released today is a turning point for those missing out, and for the future wellbeing of New Zealand. The Government now needs time to consider the recommendations in this report. I am looking forward to their response."

In August, the group, comprised mostly of academics, released a draft report, seeking community feedback on possible solutions to child poverty. With only minor changes in the final recommendations, Dr Wills said there had been a strong consensus about the best way forward.

Labour's children's spokeswoman Jacinda Ardern supported the report but was sceptical about how many of the changes would be adopted by the Government.

The report has also been endorsed by Every Child Counts, a coalition of child agencies including Unicef, Plunket and Barnardos. Its manager, Deborah Morris-Travers, said the evidence was clear and the Government needed to act.

HELPING OUR KIDS

The Solutions to Child Poverty report makes 78 recommendations.

They include "easy" solutions, and ones that will take more time and money.

Quick, cheap and relatively easy:

A "warrant of fitness" for all rental homes, ensuring they meet minimum standards for health and safety.

Government to work with finance sector to provide zero-interest or cheap loans for struggling families.

An expanded food-in-schools programme for low-decile primary and immediate schools.

Increased focus on keeping young parents in education.

Create community hubs as a one-stop shop for support services.

Longer, harder and more expensive:

Review all child benefits and refocus them on child welfare.

Create a new universal child payment for all children under 5.

Support for older children would be targeted, based on income.

Increase the number of social houses by at least 2000 a year for the next eight years.